Brain trauma or other neurological conditions may cause intracranial pressure (ICP) to rise, resulting in severe harm if it is not treated. For example, an increase in pressure may crush brain tissue, cause the brain to herniate, restrict blood supply to portions of the brain and may, in some cases, be fatal. Elevated ICP may be treated by draining cerebrospinal fluid (CSF) from the ventricles using a drainage catheter. In non-trauma cases, this procedure may be fairly simple as cranial landmarks such as, for example, Kocher's point, are well established for locating the positions of the ventricles. A hole may be drilled through the skull and the catheter inserted therethrough substantially perpendicular to the surface of the skull. In trauma cases, however, the ventricles may be shifted or collapsed making them difficult to locate without using imaging devices or ultrasound. Thus, several holes may need to be drilled into the skull and multiple catheter passes attempted before the ventricles are located.
While some surgeons prefer to secure ICP and drainage catheters via tunneling, a skull bolt may also be used to secure a catheter when additional physiological parameters such as, for example, oxygen, temperature, cerebral blood flow, microdialysis, etc., must be monitored as additional monitoring probes may be inserted through skull bolt. However, sensing zones of these monitoring probes may cross over or contact one another, resulting in artifacts and/or measuring errors.